The FIA has fitted Accident Data Recorders (ADR) to all Formula1 cars since 1997, and will also fit them to Formula 3000 cars from 2000. Data is recovered, where possible, from all incidents where control of the car has been lost, and the car either impacts another car, or leaves the track and is arrested in a run off area, or impacts a barrier.3-axis, high-g (±250g) and low-g (±50g) accelerometers, car speed, throttle and steering, the lap marker, and from 2000, yaw rate are recorded. The data is analysed to determine the deceleration on the track and the performance of circuit safety features such as run-off areas and barriers. It is sometimes possible to determine the cause of the loss of control from the data available. The data is used to compute deceleration rates for use in the FIA's Circuit and Safety Analysis System (CSAS) for the assessment of circuit safety features, assess barrier and car impact performance, and provide data for accident reconstruction and modelling. A Severity Index Coefficient (SIC) has been developed to enable impacts to be assessed quickly for their potential to cause head injuries, in order to rate them according to their need for fuller analysis.